The present invention concerns an asymmetrical, metal strip which is used to hold a gasket made of rubber-like material for auto bodies. When the metal-backed gaskets are installed, they are fastened to the relevant flanges on the car body, here in particular to the trunk lid and the doors.
The metal mounting strip ensures a sufficient adhesion to the arbor-mounted flange, and thus a secure and enduring seat for the gasket, which could not be achieved with a gasket of rubber-like material alone.
A mounting strip is manufactured by stamping out notches and slots from a metal strip as an intermediate product, bent into a U-shaped cross section and subsequently sprayed with a rubber-like, pliable gasket material.
The basic demands on such a mounting strip when used as a component of a gasket in the automobile body region are to be seen in the following points:
Good performance under tension and compression,
High tensile strength,
High mobility in all directions,
High adhesive strength,
Low weight as well as
Low manufacturing costs.
Good performance under tension and compression is especially required when the gasket is ready to be installed in the car; in particular, if the gasket can stretch or be compressed without forming creases, and if the assembler can compensate for slight discrepancies in length which occur during the manufacture of the gasket strip. This will relax the demand for the high tolerances in the manufacturing process, which reduces the costs of the process.
The demand for the highest tensile strength possible, is based upon the fact that the gasket strand is exposed to a tensile stress during manufacture, and should not tear in the process.
A gasket should be flexible in all directions, so that during assembly, the assembler can follow the specified procedure for arbor-mounting to the automobile body.
A high adhesive strength between gasket and the arbor-mounted flange on the body brings about a secure and durable fit of the gasket on the arbor-mounted flanges on that part of the body.
In order to save on production costs and fuel costs for operating the automobile, the weight of the gasket should be kept as low as possible. For this reason, aluminum is frequently used as a support material, which nonetheless has negative effects on the physical properties of the mounting strip, and therefore the thickness of the material must often be increased.
Moreover, the configuration of the mounting strip should enable the most economical manufacture possible.
DE 19725166 A1 contains information about a metal strip, which besides lengthwise notches, also has corrugation-like stamped creases. Thanks to the notches, the strip can be stretched and compressed. The stampings ensure a high adhesive strength of the gasket to the relevant body parts, and therefore allow for a reduction in the thickness and weight of the material. In the subsequent processing of the strip, the disadvantages of the stampings nonetheless become apparent, in that a special bending tool is required for bending the strip into the U-shaped cross section, so that the shape of the stamping at least not totally lost in the process. Furthermore, the stamping process requires additional tools. The finished strips are wound into spools for subsequent processing or for transport; but the stamping process leads to a greater effective strip thickness and hence a greater volume of the spool. In addition, problems arise when the metal strip is sprayed with the rubber-like gasket material.
DE 69501998 T2 and DE 3628448 C2 describe metallic strips which are manufactured according to the roll cutting process. Here the notches are not stamped out, but are cut using a tool in the shape of a thin line.
The notches notch get their characteristic shape through a subsequent stretching. With this manufacturing method, however, it is possible to create only symmetrical notches. The form that the notches take is thus quite inflexible, and is not easily brought to the desired thickness criterion. Consequently, when strips are manufactured according to the roll cutting process, owing to the consequent notch effect, a greater material thickness is required in order to achieve the same strength as those of a strip which was produced using the stamping process.
Furthermore, DE 3628448 C2 contains information on a strip whose bending behavior is said to be improved by an asymmetrical arrangement of the notches. This is attained by making short notches inside the bend, and long ones on the outside. This nonetheless leads to problems if a gasket strand is supposed to follow various different directions along a body part.
With this as a starting point, the objective underlying the invention, is to develop a metal mounting strip, which imparts a sufficient strength to the gasket of a rubber-like material for manufacture and installation, behaves well under tension and compression, possesses sufficient mobility to follow prescribed changes in direction of various body parts, and gives the gasket an adhesive strength, which would ensure a secure and enduring seating of the gasket on the arbor-mounted flange of the relevant body part. The mounting strip must fulfill these objectives in the context of the least possible weight as well as low manufacturing costs.
The objective is accomplished through a selection of the arrangement and shape of notches and slots in the mounting strip in accordance with the Characterizing Section of claim 1 and FIG. 1, which in meeting the demands for sufficient strength, mobility, good stretching and compressive behavior and high adhesive strength, permits a the metal base material to be only about 0.5 mm thick, with a correspondingly lowest possible weight, as well as low manufacturing costs with a simple manufacturing method, namely stamping.
A prototype of the invention is given FIGS. 1 and 2, and is described below with reference to the Figures.